We describe a new eusphenodontian, Lanceirosphenodon ferigoloi gen. et sp. nov., from the Upper Triassic (Norian) Riograndia Assemblage Zone (AZ) of the Candelária Sequence (Santa Maria Supersequence) of Rio Grande do Sul, Brazil. The new taxon consists of an almost complete left dentary with dentition, which exhibits a mosaic of features considered ‘typical’ of non-eusphenodontian rhynchocephalians, along with others reported for eusphenodontian taxa. It has the typical rhynchocephalian regionalized dentition with 19 teeth and also pleuroacrodont implantation; the additional dentition presents alternation of size and shape, with the last additional teeth resembling a spear in labial view. A well-developed chin is also present. Our phylogenetic analysis places Lanceirosphenodon as one of the most basal eusphenodontians and reinforces the hypothesis that Rhynchocephalia underwent an early diversification, probably in the Early Triassic, followed by an explosion in morphological disparity. Based on the ontogenetic sequence of Sphenodon, Lanceirosphenodon fitted between stages T2 and T3, representing a probable early juvenile individual. In spite of its ontogenetic stage, the set of characters present in Lanceirosphenodon, including two autapomorphies, supports its recognition as a new taxon. This new taxon increases our knowledge of the faunal diversity in the Triassic of Gondwana and more locally for the Riograndia Assemblage Zone of southern Brazil.

https://zoobank.org:pub:1849FF5A-B5D3-484B-B16C-7D952AF62A26

我们描述了一个新的真齿动物，Lanceirosphenodon ferigoloi gen。等。十一月，来自巴西南里奥格兰德州Candelária序列（圣玛丽亚超序列）的上三叠世（诺里安）里奥格兰迪亚集合带（AZ）。新的分类单元由一个几乎完整的左齿牙列组成，该齿列显示了非正齿类鼻软骨动物的“典型”特征的镶嵌图，以及其他有关真齿动物类群的报道。它具有19颗牙齿的典型的横头颅区域性牙列，还具有胸膜上颌骨植入术。额外的牙列呈现出大小和形状的变化，最后一个额外的牙齿在阴唇视图中类似于长矛。下巴也很发达。我们的系统发育分析场所Lanceirosphenodon是最基础的Eusphenodontian之一，并加强了假说：Rhchochocephalia经历了早期的多样化（可能在三叠纪早期），然后形态差异激增。根据Sphenodon的个体发育序列，Lanceirosphenodon介于阶段T2和T3之间，代表可能是早期的少年个体。尽管有其个体发育阶段，但在长尾龙象中存在的字符集（包括两个自体词型）支持将其识别为新的分类单元。这种新的分类单元增加了我们对冈瓦纳三叠纪乃至巴西南部的里奥格兰迪亚集合区的动物多样性的认识。

https://zoobank.org:pub:1849FF5A-B5D3-484B-B16C-7D952AF62A26